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Updated: May 6, 2026

Protocol for Isolating the Mouse Circle of Willis
Published on: October 22, 2016
Circle of Willis in adults
S M Al-Hussain1, A M Shoter, Z M Bataina
1Department of Anatomy, Jordan University of Science and Technology, Irbid, Jordan.
Insights
Variations in the Circle of Willis are common, with 14 types identified, including a novel one. Understanding these anatomical differences is crucial for diagnosing and treating brain artery obstructions.
Area of Science:
- Neuroanatomy
- Vascular Neurology
Background:
- The Circle of Willis is a critical arterial anastomosis at the base of the brain.
- Anatomical variations in the Circle of Willis are frequently encountered.
Purpose of the Study:
- To document the primary variations of the Circle of Willis.
- To elucidate the clinical significance of these anatomical variations.
Main Methods:
- Analysis of 50 adult Jordanian Circles of Willis.
- Detailed arterial drawing and measurement using a stereoscopic microscope.
Main Results:
- Identification of 14 distinct Circle of Willis configurations.
- 13 variations align with previously described types; one is novel.
- Detailed description of the diversity and frequency of variations observed.
Conclusions:
- Anatomical variations of the Circle of Willis are highly prevalent.
- These variations can significantly impact the presentation and management of cerebrovascular diseases.
Objective:
This study was carried out to describe the main variations of the Circle of Willis and to clarify the clinical importance of these variations, so that practitioners and the students are more alert when dealing with this subject.
Methods:
This work is based on the study of 50 Circles of Willis from adult Jordanians who died from diverse causes without signs of cerebrovascular diseases. The arteries of these circles are drawn and measured with the aid of a stereoscopic microscope provided with a drawing tube.
Results:
Fourteen types of Willis polygonals have been identified among which 13 would be assimilated to polygonals already described in previous studies. The 14th is original and seems proper to our series. We have described wide diversity of variations found within these 14 types of Willis polygonals. We presented the frequency of the different variations and discussed the clinical significance of these variations.
Conclusion:
The variations of the Circle of Willis are very common and they may have important influence on the manifestations and treatment of some diseases that are caused by obstruction of one of the arteries that supply the brain.
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